View full sizeCourtesy of Mike Stewart/Dover NurseryIf you aren't aware of their parentage, it's hard to believe the big-flowered hybrid rhododendrons are developed by crosses of wild -- or species -- rhododendrons, which have unusual, sometimes unrecognizable blooms, like R. xanthocodon.

Spring brings on a bevy of blooms. Of them all, big, bouncy rhododendrons may be the most beloved.

Closer to home, Portlanders are surrounded by offspring of the "When I was a kid, our entertainment in spring was to go up to Mount Hood -- with thousands of others -- to see the rhododendrons."

View full sizeThe OregonianThough we associate rhododendrons with large, showy flowers, some of them have a personality defined by the size and shape of their foliage, as well as a fuzzy covering called indumentum like that found on R. sphaeroblastum. Bark can also add interest. This diversity is not surprising when you consider the thousands of varieties, including 30,000 hybrids and more than 1,000 species.

pink-flowered Pacific Coast native Rhododendron macrophyllum and other wild species. The decades-old hybrids decorate every part of the city, especially older neighborhoods such as Laurelhurst, Mount Tabor and Eastmoreland. Typically animated by ebullient flowers in shades of pink and purple, these plants are from the land of obvious beauty. The world of species rhododendrons (those that are found in the wild, as opposed to hybrids created by humans) is subtler, but no less beautiful. Flowers often take a back seat -- or at least a

View full sizeCourtesy of Mike Stewart/Dover NurseryMike and Maria Stewart's enthusiasm for rhododendrons, including the giant-leafed R. sinogrande and pink-flowering 'First Date,' is reflected in the 1,200 different varieties that they grow at Dover Nursery in Sandy.

side seat -- to foliage, form and texture, attributes that give them year-round influence.

The Stewarts, who grow about 1,200 rhododendron varieties and sell 40,000 plants a year from their wholesale nursery in Sandy, say the market for species rhododendrons has grown dramatically.

Some of that has to do with the Stewarts, who slipped a few species surprises into shipments at no charge.

"They'd unload their order, and say, 'That's a rhody?'" Mike says. The wildly diverse shapes, sizes and texture of foliage, from the smaller-than-a-fingernail

View full sizeCourtesy of Thomas GresslerPaths in the Cecil and Molly Smith Garden move through a mature and rare collection of rhododendrons complemented by ferns, wildflowers, cyclamen, fawn lily and trillium.

leaves of R. litangense, a dwarf from China that gets 1 foot tall by 2 feet wide at most, to the tree-sized R. sinogrande and R. rex

If all you knew were the big balls of hybrid flowers, the blooms of their cousins would surprise you. Those with their tropical-looking, paddle-size leaves up to 2 feet long, offers something for everyone. On some plants, a fuzzy little miracle called indumentum coats the undersides of leaves like suede in shades from palomino gold to glowing garnet.

View full sizeCourtesy of Keith White'Double Winner' (far left) was bred by the late Cecil Smith, a renowned rhododendron expert, who, with his wife, created the Cecil and Molly Smith Garden in St. Paul. The hybrid was named after winning best in show the first time he presented it at the Eugene and Portland shows of the American Rhododendron Society.

of R. saluenense look amazingly like pansies. R. macrosepalum linearifolium (no need to pronounce it, just enjoy) puts out a starburst of fuchsia-pink strings. On R. spinuliferum, salmon-colored tubes stand straight up with red-tipped stamens erupting from the top.

Mike and Maria want to show them all. So on an early March day after a surprise snowstorm, they walk through one of18 greenhouses, picking out pots and repeating over and over, "This is one of our favorites." Obviously, "one" is not the word to use, and two hours is not nearly long enough to give a tour, not with hundreds of plants to show off, including hybrids and deciduous azaleas. Hybrids aren't going anywhere. With 30,000 already on the market, breeders keep on tweaking, arranging marriageslike old-fashioned parents. Orange-and-yellow bicolor flowers like those sported by 'Nancy Evans,' 'Seaview Sunset' and 'Honey Butter' are the

hottest trend, with dark purples a close second.

How to choose? You don't. Just make room in the garden.

AMERICAN RHODODENDRON SOCIETY CONVENTIONWHAT: About 20 speakers covering a wide range of topics such as dwarf rhododendrons; fertilizer and organic options; grafting; hybridizing for beginners; photography; companion plants such as Japanese maples, conifers, clematis and hydrangeas. INCLUDES: Plant and book sale; afternoon tours of public and private gardens. WHEN: May 11-15 WHERE: The Heathman Lodge, Vancouver, Wash. COST: $49 general registration; additional fees for tours, banquet and barbecue.INFORMATION: American Rhododendron Society; or Loni Welsh, 503-663-6987, GROWING TIPSRhododendrons require three conditions to thrive.

Light, crumbly, well-drained soil with a pH in the 5 to 6 range. Amend with bark dust, compost or sawdust until consistency is light and crumbly and drains freely. Soils in the Northwest tend to be on the acidic side, so annual application of fertilizer is all that’s usually required to keep pH adjusted.

Water to keep evenly moist during first year. When established, water during hot summer spells.

Fertilize once a year in about March with granular fertilizer formulated for rhododendrons.

R. saluenense: A May bloomer with open-faced, rosy purple flowers that look almost like pansies. A mounding dwarf plant that gets 1 foot tall in 10 years. Hardy to minus

R. campylogynum var. myrtilloides: Thimble-shaped, lavender-pink flowers, each supported by a single stem. Blooms in April on an upright, dwarf shrub that gets 1 foot tall by 3 feet wide in 10 years. Good for bonsai. Hardy to minus 10. 'Peter Bee': Yellow flowers in April. A mounding, vigorous shrub that is wider than it is tall (30 inches tall and 3 feet wide) in 10 years). From Warren Berg, who also hybridized 'Wee Bee,' 'Patty Bee,' 'June Bee,' 'Queen Bee' and many others. Hardy to minus 5. 'Yummy Yak': Peachy-pink May flowers on a compact shrub that grows wider than tall (3 feet tall by 4 feet wide in 10 years). Undersides of the leaves have a fuzzy, beige covering called indumentum. Hardy to minus 5.

'Taurus': Red buds throughout winter opening to red flowers in April. Dark green leaves on a large shrub up to 6 feet in 10 years. Dark green leaves. Hardy to minus 5.